The suggestion of using TRIM does not (in all cases) protect against accidental data visibility to the "next random guy", it doesn't even protect from some other current random guy as your container could have moved and left another user with access as their new container got created over the space you used to occupy - so unless you have another method that hasn't been discussed yet there isn't a point in between: you protect yourself from both or you protect yourself from neither.
If you need to be sure your instructions to wipe data do protect you from that random other guy then you either need to use good encryption (it doesn't have to be full volume encryption but once you get to the point of caring it is probably easier to go the whole hog than do it piecemeal) or you need to have dedicated physical storage (something a VPS provider generally doesn't offer.
Of course the provider could instigate full data wiping for all relevant operations, but that imposes I/O load that will affect all other users of the given host machine(s) unnecessarily (I say "unnecessarily" because most won't care as their bulk data is not sensitive and they've invalidated associated things like SSH keys anyway, the host will take the attitude that if your data is sensitive you need to take measures to protect it).
If you need to be sure your instructions to wipe data do protect you from that random other guy then you either need to use good encryption (it doesn't have to be full volume encryption but once you get to the point of caring it is probably easier to go the whole hog than do it piecemeal) or you need to have dedicated physical storage (something a VPS provider generally doesn't offer.
Of course the provider could instigate full data wiping for all relevant operations, but that imposes I/O load that will affect all other users of the given host machine(s) unnecessarily (I say "unnecessarily" because most won't care as their bulk data is not sensitive and they've invalidated associated things like SSH keys anyway, the host will take the attitude that if your data is sensitive you need to take measures to protect it).